C.....Subroutine to convert (h,s,v) values to (r,g,b) values.
      subroutine hsvrgb(h,s,v,ir,ig,ib)
      implicit real (a-h,o-z)
      real pqvt(4)
      integer irpnt(6),  igpnt(6),  ibpnt(6)
      data irpnt/3,2,1,1,4,3/,igpnt/4,3,3,2,1,1/,ibpnt/1,1,4,3,3,2/
C.....
C     input:   0 <= h <= 360    (hue)
C              0 <= v <= 1.0    (value or brightness)
C              0 <= s <= 1.0    (saturation)
C     output:  0 <= ir,ig,ib <= maxval
C.....
      if (s .eq. 0.0) then
         ir = 255.0*v
         ig = ir
         ib = ir
         return
      endif
      if (h .eq. 360.0) h=0.0
      h = h / 60.0
      i = int(h)
      f = h-i
      pqvt(3) = 255.0*v
      pqvt(1) = pqvt(3)*(1.0-s)
      pqvt(2) = pqvt(3)*(1.0-s*f)
      pqvt(4) = pqvt(3)*(1.0-s*(1.0-f))
      i  = i + 1
      ir = pqvt(irpnt(i))
      ig = pqvt(igpnt(i))
      ib = pqvt(ibpnt(i))
      return
      end